The present invention generally relates to electronically beam steering phased array antennas, tunable phase shifter, and tunable dielectric capacitors.
Multipath delay causes the information symbols represented in an 802.11 signal to overlap, which confuses the receiver. This is often referred to as intersymbol Interference (ISI). Because the shape of the signal conveys the information being transmitted, the receiver will make mistakes when demodulating the signal's information. If the delays are great enough, bit errors in the packet will occur. The receiver won't be able to distinguish the symbols and interpret the corresponding bits correctly.
When multipath strikes in this way, the receiving station will detect the errors through 802.11's error checking process. The CRC (cyclic redundancy check) checksum will not compute correctly, indicating that there are errors in the packet. In response to bit errors, the receiving station will not send an ACK to the source. The source will then eventually retransmit the signal after regaining access to the medium.
Because of retransmissions, users will encounter lower throughput when multipath is significant. The reduction in throughput depends on the environment. As examples, 802.11 signals in homes and offices may encounter 50 nanoseconds multipath delay while a manufacturing plant could be as high as 300 nanoseconds.
Thus, there is a strong need in the RF industry and more particularly in the wireless local area network industry for wireless devices, networks, methods and systems which may overcome multipath and other RF transmission shortcomings to improve performance in a wireless local area network.